Hydraulic system



H. ERNST ET AL HYDRAULIC SYSTEM Filed May 11. 1929 Suva/tow di Q r Bw@ w ltbl Patented Dec. 8, 1931 UNITED STATES PATENT OFFICE HANS ERNST AND LETER F. NENNINGER, OF CINCINNATI, OHIO, AssI'GNons To THE CINCINNATI MILLING MACHINE COMPANY, or CINCINNATI. OHIO, A CORPORATION 0F OHIO Application led May 11,

Hydraulic propulsions, as heretofore provided, are of two distinct types, to wit:- One which seeks to produce a uniform rate of advance of an actuated member b delivering into an hydraulic motor, ata vo umetrically uniform rate, what may be termed pushing oil, and the other in which a uniform rate of movement isobtained by diminishing, at a vOlu-metric'ally constant rate, a supply of movement-resistingoil which serves to oppose themovement of the actuatedfmember under the influence of the pushing oil.

The present invention relates primarily tosystems of the former type and it seeks to render such systems more eicient under varying conditions such,`for example as are encountered when they are employed to effect, selective! fast and slovs1 movements of a milling mac me work-table or other translatable element.

The hydraulic system provided by this invention satisfies a number of desiderata. First, it effects arelativel rapid movement of the translated element 1n either direction. Second, it maintainsa hi h'back .pressure on the exhaust end of the hydgraulic motor,.there by precluding jumping othe piston .and its Connected parts by .irregular action 'of the tool on the work, and :-third, it insuresv the delivery of pushing Oil into the intake vend Of the hydraulic motor at a volumetrically uniform rate.'`

AThis invention proposes an improved sys.- tem in which each of these three functions is performed by an individual pump, 'eachof which is adapted to perform its function in a most efficient manner and with a minimum amount of power; the exhausting of large quantities of oil against high back pressures, as in certain prior systems, being wholly Obviated.

` In the annexed drawings, forming a part of this disclosure, Figure 1 is a diagrammatic viewof the improved hydrauliesystem, ,the`

controlling valves thereof being so set as to effect rapid traverse movement of the actuated element to the left. Fig. 2 is a similar view with the valves set in a different position thereby to effect slow feeding movement of the actuated element to the left` the rate of l,ings the improved ydraulic to advantage when embodied 1n HYDRAULIC SYSTEM asas. smal No. 362,414.

feed being determined by the action Ofa variable deliver pump connected with the intake lend of the ydraulic motor. A

Referring more s eciically to the drawstem is disclosed as comprisinga reservoirR adapted to contain a supply of actuating li uid, preferably oil; an hydraulic motor compris- -ing a cylinder 1 and piston 2, and a plurality of pumps, valves and conduits, later tobe descrlbed, connecting the reservoir and the mot`or. `The motor is, of course, intended to do work and this ma be effected by having the piston 2 connecte as by a piston rod V3, with a reciprocatory element or table 4. AFor the purpose of this disclosure the element 4 ma)`r` be considered to be the work.-

table of a milling machine inasmuch as the features of this invention ma be employed that type of machine tool.

The umps embodied in this systemcomprise a Ow pressure high capacity pump RT, ada ted toleifect rapid traverse movements of t reciprcatory table 4; a low ca acity high pressure booster pump B adapted) to be connected to the exhaust end 'of the cylinder 1,- to build u in said end a high resisting pressure 5 an a high pressure pum Z hav- `1n its discharge .port connected wit the inta end of said cylinder and se i to inject oil thereinto at a volumetrically uniform rate'. The pump Z ma receive oil -from any suitable source but pre erably it is connected to receive Oilrrom the-exhanst .endo-f the hydraulic motor. To enable the table tobe moved at an desired uniform rate, the pump Z is preferably of the variable delivery type which, by means of adjustment ma be caused 1 to deliver oil into the intake end o the motor at any desired volumetrically uniform rate from zero to the maximum capacity of the Pump- Intermediate the pumps RT, B and` Z and the hydraulic motor H, are two valves, one

vL, which 'serves' as a selector or main conf serves either to connect the motor H with As 1 ftircuitedt In'sther Words, oil

the valve L, as shown in full lines' in the drawings, or to isolate the motor from theV valve L and the pumps, as vshown in dotted lines in Fig. 2, thereby to tra the oil in the opposite ends of the motor when it is desired to lock the table 4 against movement in either direction. vThe constructon and operation of the valves L and M' are clearly shown andY described in our application, Serial Number 220,721 filed Se tember 1 5, 1927, and also in British latent o. 297,104. Detailed illustration and description thereof,'in this application, is therefore deemedunnec- Eig. 1 shows the. vvalvesll.' and .M so set that the pumps B and Z are isolated from the motor H and the rapid traversepump RT is connected to eil'ect rapid movement of the piston 2 and table 4 to the left. A -In this setting of the valves the rapid traverse pump draws oil from the reserver R through conduit 5 and discharges it throu h conduit', pfrt 7 in valve L, conduit 8, t rou h valve Vand conduit 9 into the right en of the cylinder 1. At the same time oil in the left -end of the cylinder escapes freely through' conduit 10, valve M, conduit 11, port v12, m valve L, and through conduit 13 to voir.

A relief line 14, controlled by a relief valve 15 connects the discharge side of the pump with the reservoir and thereb .limits the pressure which that pump may build up in the motor and returns to thereservoir any excess oil delivered by the pump.

shown in Fig.'1 the pump Z is short ssed i351 the pum Bows outwardl throu 16, ugh a port 1 the 4valve L and back through a conduit 18 tothe intake 'port of the pump thereb maintaining. ffl-ee` circulation o oil. elow-capacity high pressure booster pump B 4draws smallfquun;y tities of oil from? the reservoir through a con duit 19 and discharges it throughaconduit 20 connected with. the intake Iport ofthe pump Z. In this setting ofthe valves -the output of the pum B 1s reuired. only to maintain the pum and con uits connected therewith filled with oil. The excessoil `de;-y livered'by the ump B is exhausted back into thereservoir through an exhaust line 21 controlled by a high pressure relief valve 22.A

.Y `From the tion shown in. Fig.1, vthe valve L may shifted, as described in the agplication abQYe referred to,to connectthe le end of the motoHwith the rapid tra vom pump BT me comme 'ng-1.1 end of the motor with the reservoir, thereby to e'ect rapid traverse movement of the piston 2, and 4 ai-ts therewith, mythe right. ilewisethevalve maybe the reserthe Aconduit to the position shown in Fig. 2, in which` the pump RT is short circuited, having its outlet conduit 6 connected, as by ort 23 in the valve L, with the drain conduit 13. In this position of the valve, the booster pump am -Bisconnected through conduit 18, port 24, conduit 25, through valve M and conduit v10 with the left end of the hydraulic motor H, therebymaintaining a hilgh resisting pressure therein, the value of w ich is determined by the relief valve 22. The pump Z has its, discharge port connected, by conduit 16, port 26, in' valve L, conduit 8, through valve M and conduit 9, to the right end of the motor As hereinbefore stated Vthe pump yZ might receiveits iluid from an suitable source, such for example, as'by ing connected. directly withihe reservoir R. Preferably, however, it has its intake port connected with vthe conduit 18 which serves as a dischar e for the oil in the exhaust end of thevcylginder 1.' Thus the oil exhausted from the left end of the motor the pump Z` andl is forcibl the right endl .thereof there eifect, a closed circuit. Y

The ollce of the pump B is, as previously stated, to maintain a high pressure inthe exhaust end of the motor H and also to maintain the system completely filled with oil. It will readil be erceived that by havin the 'intake en of t e pump Z connected Wit the exhaust end of the cylinder l'and the hi h y` forming', in 9o pressure pump' B also yconnected with t e same end the pump B may perform its rev quiredfunction by passing only a very small quantity of Oil.

y In certaina'pplications of vhydraulic sys-V tems, such for exam le, as where they `are eifectxfee movements of thev Work-table of .n..milling machine in which the action/ofthe cutter :on` thev work tends to move the table. in the direction of feed, in order to ,produce the required 'margin of Safet it is necessary that tlie'rclief valve, whic controls the exhaust of iluid from'the motor, be set to withstand a pressure u to lbs. per square inch. Itwil1, there ore, be perceived l' that "the exhaust' of, any sub? stantial4 amount ofoil through this 'valve 116 would nthansmn non of asub- A stantal aihpunt of weran jlikewisewould esultin the undesirable heating of the o il. These objections have been particularly noticeable priorfsystems in which a single '120 high capacity pump has been utilized to effectra id trayerse and'to producethe re-` quired adk.' pressure on the'sy'stern. The

resent invention overcomes these objections yshqrt circiitngthe rapid traverse: pump 1525 when ltraverse` is'not requiredg'nd inga separate` low capacity high lpressure to' produce the required back pressure; Vth '"CHSDOD and` arrangement all ofthe adviitages are obtained andV the d is':A

los

advantages incident to the exhausti of great quantities of oil against a high ack` pressure are obviated.

From the position shown in Fig. 2 the valve Lmay be shifted to connect the intake port of the pump Z with the rightend of the cylinder 1 and the discharge port thereof with -the left end of said cylinder, thereby to effect feeding movements of the table 4 to the right.

Under certain conditions it may be desirable to discontinue the feed of the table and to lock it against movement in either direction. This may be effected by shifting the valve M to the position shown in dotted lines in Fig. 2 whereby the conduits 9 and 10 are both closed against exhaust and the pump Z is short circuited by having its discharge conduit 8 connected with the return conduit 25.

Without further analysis, the foregoing will so fully reveal the gist of this invention that others can, by applying current knowledge, readily adapt it for various utilizations by retaining one or more of the features that, from the standpoint of the prior art, fairly constitute essential characteristics 0f either the generic or specific aspects of this invention and, therefore, such adaptations should be, and are intended to be, comprehended within the meaning and range of equivalency of the following claims.

aving thus revealed this invention, we claim as new and desire to secure the following combinations and elements, or e uivalents thereof, by Letters Patent of [tlnted States 1. An hydraulic system combining a motor; a reservoir; a high capacity pump adapted to be' connected draw oil from said reservoir and to deliver it into said motor to effect relatively rapid actuation thereof; a second pump adapted to be connected with an intake side of said motor to deliver oil thereinto when the first mentioned pump is disconnected from said motor, thereby to effect relatively slow actuation thereof; and a third pump adapted to have its discharge port connected with the exhaust side of said motor when said second pump is connected to the pump thereby to maintain therein a pressure counter tothe pressure built up in'the intake side thereof by said second ump.

2, An hy raulic system combining a motor; a reservoir; a first pump of high capacity a-dapted to be connected with said motor and to draw oil from said reservoir and to deliver it to said motor to effect relatively ra id actuation thereof; a .second pump adliipted to be connected with one side of said motor to deliver oil thereinto, thereby to effect relatively slow actuation thereof; a third pump adapted to have its dischar e port connected with the exhaust side of said with said motor and to` motor when said second pump is connected with the intake side thereof thereby to maintain therein a pressure counter to the pressure built up in the intake side by said second ump; and a valve for connecting one of the rst two mentioned pumps with said motor and for short circuiting the other of said two pumps.

3. An hydraulic system combining a motor; a reservoir; a first pump of high capacity adapted to be connected with said motor and to draw oil from said reservoir ai'id to deliver it to said motor to effect relatively rapid actuation thereof; a second pump adapted to be connected with the intake side of said motor to deliver oil thereinto, thereby to effect relatively slow actuation thereof; a third pump adapted to have its dischar e port connected with the exhaust side of said motor when said second pump is connected with the intake side thereof thereby to inain tain therein a pressure counter to the pressure built up in the intake side by said ,second pump; and a valve for selectively connecting either of said first and second pumps with either side of said motor to effect forward or reverse actuation thereof and for simultaneously therewith shortcircuiting the other of said two umps.

4. An hydraulic s stem combining `a motor; a reservoir; a rst pump of high ca pacity adapted to be connected with said motor and to draw oil from said reservoir and to deliver it to said motor to effect relatively rapid actuation thereof; a second pump of high pressure adapted to have its discharge port connected with the intake side of said motor to deliver oil thereinto when said first pump is disconnected from said motor; a discharge conduit connected with the exhaust side of said motor and extendin to said reservoir a hi h pressure relief va ve embodied in said conduit; and a third pump of high pressure and low capacity receiving oil from said reservoir and connected with the eX- haust side of said motor when said second ppmp is connected with the intake side thereo 5. An hydraulic s stem combining a motor; a reservoir; a fifi-st pump of high capacity adapted to beconnected with said motor and to draw oil from said reservoir and to deliver it into said motor to effect relatively rapid actuation thereof; means to short circuit said pump; a second pump of high pressure having its discharge port connected with the intake side of said motor to deliver oil thereinto when the first pumpY is short circuited; a discharge conduit connected with the exhaust side of said motor and with the intake port of said second pump; a third pump of high pressure receiving oil from said reservoir and injecting it into said discharge conduit; and a high pres .shall receive 'of the secon sure relief valve in said discharge conduit to limit the maximum pressureftherein.

6. An hydraulic system. combining a motor; a reservoir; a high capacity low pressure pump adapted'to draw oil from said reservoir and to deliver it into either end of said motor;` conduits, and valve means therein, to determine which end of said motor the oil from said pump` and to connect the oth'er end thereof with said reservoimsaid valve ,means also serving at another time to short circuit said pump; a second pump of the variable delivery type having its discharge port connected with one end of said motor and its intake port connected with a discharge conduit extending from the exhaust end of the motor when the first pump is short circuited, said valve means also serving to determine which end of the motor shall be connected with the discharge ort of the second pump; and a third pump ci) high prf-.ssure and low capacity delivering oil into said discharge conduit thereby to maintain the exhaust end of said motor and said discharge conduit filled with oil under high pressure.

7. An hydraulic system as set forth in claim 5 embodying an auxiliary valve intermediate said main valve and said motor and adapted to isolate both sides of said motorA from said pumps and from said discharge conduit to lock the piston of said motor against movement in either direction.

8. An hydraulic system combining a motor; a first pump adapted to be connected to deliver oil into said motor to effect rapid actuation thereof; a second pump adapted to have its intake and discharge ports connected respectively wit the opposite sides ofv said motor to eect slow actuation thereof; and a third pum connected with the intake side pump and thereby adapted to maintain a high rpressure on the exhaust side of said motor. i

In witness whereof, we have hereunto subscribed our names. Y

HANS ERNST. LESTER F. NENNINGER.

sure relief valve in said discharge conduit'to limit the maximum pressure therein.

6. An hydraulic system combining a motor; a reservoir; a high capacity low pressure pump adapted to draw oil from said reservoir and to deliver it into either end of said motor; conduits, and valve means therein, to determine which end of said motor .shall receive the oil from said pump and to connect the other end thereof with said reservoir; said valve means also serving at another time to short circuit said pump; a second pump of the variable delivery type having its discharge port connected with one end of said motor and its intake port connected with a discharge conduit extending from the exhaust end of the motor when the first pump is short circuited, said valve means also serving to determine which end of the motor shall be connected with the discharge ort of the second pump and a third pump o high pressure and low capacity delivering oil into said discharge conduit thereby to maintain the exhaust end of said motor and said discharge conduit filled with oil under high pressure.

7 An hydraulic system as set forth in claim 5 .embodying an auxiliary valve in- 1 termediate said main valve and said motor and adapted to isolate both sides of said motor from said pumps and from said discharge conduit to lock the piston of said motor against movement in either direction. 8. An hydraulic system combining a motor; a first pump adapted to be connected to deliver oil into said motor to effect ra id actuation thereof; a second pump adaptedl to have its intake and discharge ports connected respectively with the opposite sides of said motor to effect slow actuation thereof; and a third pumpjconnected with the intake side of the second pump and thereby adapted to maintain a high pressure on the exhaust side of said motor.

In witness whereof, we have hereunto subscribed our names.

HANS ERNST. LESTER F. NENNINGER.

CERTIFICATE 0F CORRECTION. 1

Patent No. 1,835,977. Granted December 8, 1931, y to HANS ERNST ET AL.

lt ia hereby certified that error. appears in the printed specification of the' above numbered patent requiring correction as follows: Page 3, `line 5l, claim 1, forvahc word "pomp" second occurrence read motorpand that the said Letters Patent'johould be rcad with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 9th day of February, A. D. 1932.

- M. It 0611.

(Seal) Acting Commiaiioner of Patents.

CERTIFICATE 0F CORRECTION.

Pneu: No. 1,835,911. Granted December s, 1931,10

HANS ERNST ET AL.

lt is hereby certified that error appears in the printed specification of thc above numbered patent requiring correction as follows: Pege 3, line 5l, claim l, for the word "pump" second occurrence read motor; and that the said I .etters Patent :'lhould be read with this correction therein that the same may conform to the record of the cese in the Patent Office.

Signed and sealed this 9th day of February, A. D. 1932.

AM--Js MOiIIC (Seul) Acting Commisiidner of Patente. 

